The present invention generally relates to digital audio systems and particularly concerns the incorporation of a digital audio system in a high definition television broadcast system.
A number of HDTV systems have recently been proposed which provide for the digital transmission of a wideband video signal over a standard 6 MHz television channel. These systems typically initially compress a wideband video source signal and then transmit the compressed signal over a selected 6 MHz television channel. While various video compression systems are known in the art, temporally oriented systems seem to be presently preferred. Transmission may be effected, for example, by encoding the binary data representing the compressed signal as a series of N-level symbols, each symbol thereby representing N/2 bits of binary data.
Obviously, it would be highly desirable to provide for the transmission, preferably in a digital format, of an equally high quality audio signal as an accompaniment to the video signal. There area a number of known digital audio systems which are capable of providing the desired level of performance, but these systems have not been designed with a television application in mind. As a result, these systems cannot be directly incorporated into an HDTV system without causing certain problems. For example, since the sampling rates used in prior art digital audio systems are not compatible with the video timing signals in most HDTV systems, disturbing audible beats may result upon reproduction of the audio signal in an HDTV receiver. Also, the data rates of such audio systems are not compatible with HDTV transmission data rates which can lead to problems in accurately reproducing the audio signal, and particularly in effecting accurate error correction of the received audio signal.
It is therefore a basic object of the present invention to provide an improved HDTV system including compatible video and audio subsystems.
It is a more specific object of the present invention to provide an improved HDTV system including video and audio subsystems having compatible timing characteristics.